2-Furamide, a structural analog of the diuretic furosemide, produces centrilobular liver necrosis and renal tubular necrosis in mice. Pretreatment with inhibitors of metabolism decreased irreversible binding of metabolite and glutathione depletion in target organ tissue while concomitantly protecting against histologic tissue damage. Induction with phenobarbital tended to enhance hepatic necrosis, glutathione depletion and covalent binding while having little effect on the corresponding renal parameters. Covalent binding of radiolabeled material to mouse renal or hepatic microsomes was dependent on NADPH, oxygen and temperature and was inhibited by a carbon monoxide-oxygen atmosphere. These experiments demonstrate that 2-furamide undergoes in vivo and in vitro activation in the mouse liver and kidney to reactive species producing hepatic and renal necrosis. The differential in vivo target organ response to phenobarbital induction and in vitro metabolite binding studies suggest that renal necrosis results from in situ metabolic activation rather than hepatic metabolism. Thus, the spectrum of hepatic and renal lesions induced in experimental animals by simple 2-substituted furans and thiophenes, as well as more complex structural analogs may result from organ specific metabolic activation.